The present invention relates to local combined telephone and alarm systems.
More particularly, the invention concerns a local telephone and alarm system, including:
a central base comprising:
a) two-way radio communication means,
b) a central electronic unit adapted to make the radio communication means of the base work according to a local numeric communication protocol, this protocol being two-way and multiple access (in other words, this protocol allows the base, by emission and by reception, to communicate, xe2x80x9csimultaneouslyxe2x80x9d with several of its peripherals, this multiple access being notably obtained by time division [TDMA type protocols] and/or by multiple carrier frequencies, or also by spread spectrum),
c) and a link which allows communication with a public telephone network,
and peripherals including at least one detector adapted to detect at least one predetermined emergency situation and to communicate by radio with the base according to said local communication protocol, this detector being adapted to send an alarm message to the base when it detects said emergency situation, and the central unit of the base being adapted to provoke at least one alarm reaction when it receives the alarm message from the detector, the central unit of the base being also adapted to communicate by radio with at least one telephone set (effectively present or not) according to the local communication protocol.
An example of one such combined local telephone and alarm system, using the DECT communication protocol (notably defined by ETS 300 175-1 to ETS 300 175-9 norms, as decreed by ETSI) for the radio link between the base and the telephone sets and the detectors, was described by A. Carminxc3xa9 (xe2x80x9cMultimedia over DECT: the enabling technology for multi-application wireless systemsxe2x80x9d, Philips telecommunication review, vol. 52, No4, October 1995, p 9-11).
One advantage of this system is to combine in the same apparatus, on the one hand, the central base functions of a local cordless telephone network, and on the other hand, the functions of an alarm central unit, leading to benefits in terms of cost savings and size. Furthermore, by the fact that the local communication protocol is multiple-access, the different units communicating with the base do not interfere with each other.
However, in its function as an alarm system, this currently known system displays an insufficient degree of reliability, in so far as no alarm message can reach the base if the detector is defective.
In particular, this situation may arise:
in the event of detector failure,
and, when it concerns an intrusion detector, if a burglar manages to destroy this detector before it has had time to send the alarm signal to the base.
The present invention aims notably to overcome this drawback.
To this end, according to the invention, a local combined telephone and alarm system of the type in question is characterized:
in that the base central unit is adapted to make the communication means of said base emit, at regular time intervals, scanning messages to the detector,
in that the detector is adapted to send an acknowledgement message to the base each time it receives a scanning message,
and in that the base central unit is adapted to check whether the base has successfully received the corresponding acknowledgement message for each scanning message, and to identify the defective detector and to activate at least one predetermined checking reaction if the acknowledgement message corresponding to a scanning message is not received by the base within a predetermined time period after the emission of said scanning message (this checking reaction is adapted to directly determine or provoke determination of whether the detector has simply broken down or if it is necessary to activate an alarm reaction).
Owing to, these dispositions, natural or provoked detector failures are rapidly identified by the base, which can then react in an appropriate way, for example:
by indicating this fault to a human operated surveillance station for checking the situation,
and/or by directly checking whether several detectors have simultaneously become defective, so as to determine in this way if the alarm has to be activated immediately, etc.
In the preferred embodiments of the invention, one may possibly use one and/or other of the following dispositions:
the local communication protocol makes provision for time dividing the radio communications in frames themselves regrouped in sets of successive frames of predetermined duration, inferior to 1 s, each set of frames comprising, for each peripheral, a call time slot of duration much inferior to said predetermined duration, during the course of which the base is capable of emitting at least part of a call message to said receptor, at least the detector is electrically autonomous and is adapted to be either in an active state where said detector communicates with the central base, or in a stand-by state where said detector cannot communicate with said central base, the detector being adapted to remain in a stand-by state for the majority of time and go into an active state uniquely:
either when the detector""s sensor detects said predetermined emergency situation
or after every n sets of frames during the call time slot corresponding to said detector, n being an integer at least equal to 3, and the base is adapted to emit said scanning messages to the detector during n sets of successive frames;
the local communication protocol is the DECT protocol, the duration of each set of frames being 640 ms, and n being equal to 3;
the local combined telephone and alarm system furthermore comprises at least one telephone set adapted to radio communicate with the base according to the local communication protocol;
each scanning message sent by the base to the detector constitutes a request for establishment of two-way communication addressed specifically to said detector, the acknowledgement message sent back by the detector being constituted by the establishment of said two-way communication between the detector and the base;
each scanning message sent by the base to the detector constitutes a unilateral paging message addressed to all of the peripherals, containing a predetermined code requesting at least one detector to establish two-way communication with the base, the acknowledgement message sent back by the detector being constituted by the establishment of said two-way communication between said detector and the base;
each scanning message sent by the base to the detector consists in the establishment by said base, of two-way communication with this detector, the acknowledgement message sent back by the detector being constituted by at least one message received by the detector and confirming that said two-way communication has been successfully established;
the time intervals separating two scanning messages to the detector, are inferior to 3 minutes;
the base central unit is adapted to communicate with a tele-surveillance centre, said alarm and checking reactions each comprising the establishment of a communication link between the base and the tele-surveillance centre, and the central unit being adapted to, when it activates one of said alarm and checking reactions and when the public telephone network line is already in communication with other than the tele-surveillance centre, interrupt this communication: in this way the priority of communication with the tele-surveillance centre is guaranteed above all other communication, without having to carry out any other particular connection to the base, even when said base is connected with the public telephone network by wire;
the local combined telephone and alarm system furthermore comprises at least one visual surveillance aid which includes an electronic camera and which is adapted to communicate with the base by radio according to the local communication protocol, so that images can be captured and sent to said base, the base being adapted to re-transmit these messages to the tele-surveillance centre;
the local combined telephone and alarm system furthermore comprises at least one acoustic surveillance device which includes a microphone and which is adapted for radio communication with the base according to the local communication protocol, so that sounds can be captured and sent to said base, the base being adapted to re-transmit these sounds to the tele-surveillance centre;
the local combined telephone and alarm system includes several detectors, the base central unit being adapted to:
memorise detector failures as well as the times when they become defective,
when said base central unit determines a detector as defective and activates the control reaction, check if any of the other detectors are defective,
and in the affirmative, activate said alarm reaction in function of a number of defective detectors and the chronology of failures;
the local combined telephone and alarm system furthermore comprises an interface device allowing communication with a human operator, this interface device being adapted to communicate with the base central unit in accordance with the local communication protocol, and the base central unit being adapted in order to send break-down messages to this interface device each time a detector is determined as defective;
the system furthermore comprises a distress call portable unit which is adapted to communicate by radio with the base according to the local communication protocol and which includes a means for activating distress calls, a loudspeaker and a microphone.